Factual error: At the onset of the baseball game, take a look at the Angel's catcher as Mariner Jay Johnstone steps up to bat. You will see he is wearing just a standard baseball hat under his catcher's helmet. MLB rules requires some form of certified (protective inside and out) plastic helmet for catchers, and thus this would not be allowed.
Visible crew/equipment: At the end of the film when the guy in the wheelchair is rolling down the stairs you can see a burst of gas (presumably from a CO2 cylinder) fire the man up.
Visible crew/equipment: In the opening sequence, the camera's shadow on which the car roof and siren are mounted is visible as it enters the house.
Other mistake: Pay attention to one of the early innings of the baseball game as one of the Angels players hits a home run. Though probaby intentionally set up this way as to avoid any problems of "logo patents" and such with the real life MLB California Angels team, he is wearing a helmet without the team logo on it.
Continuity mistake: In the scene where Frank is in the driving school car chasing the doctor, right after Frank says, "I know a shortcut. Turn left here", we see two brief shots of the doctor's car, one from the inside of the car and the other from the outside as he is turning around a corner. In both shots the rear window is shattered. However, it is only four shots later that Frank shoots at the doctor's car, shattering the then intact rear window.
Continuity mistake: After deactivating the hypnosis, Ludwig has the remote in his left hand. A second later, it's in his right hand.